Our (@DICE_Kent @wildbusiness & team) evaluation of England's biodv compensation policy 'Biodiversity Net Gain' is out in @ConLetters, adding to academic lit evaluating outcomes of biodv compensation systems conbio.onlinelibrary.wiley.com/doi/full/10.11…. Takeaways for academic #offsetting peeps: 🧵
This adds to the relatively few jurisdictional evaluations that use real data, such as Gibbons et al. 2018 for New South Wales onlinelibrary.wiley.com/doi/abs/10.111…, & classic work in Canada by Quigley & Harper link.springer.com/content/pdf/10…
The evidence surrounding compensation systems is getting better; there have been 3 quantative reviews of outcomes in the last few years. 1 by @theis_seb conbio.onlinelibrary.wiley.com/doi/abs/10.111…; 1 by Josefsson et al. sciencedirect.com/science/articl…; 1 by us conbio.onlinelibrary.wiley.com/doi/full/10.11…
So, key takeaways for academics. 1) Metrics. The Biodv Metric used in Net Gain is simple, easy to use for non-specialists, non-replicable, & severely open to judgement-based variability. It's not been empirically evaluated in the field, so that's a huge gap.
I worry we're heading towards smtg shown by @RobertsonMorgan & co, where Metric becomes the be-all-end-all, crowding out ecological complexity & other biodv info journals.sagepub.com/doi/abs/10.117…. Have seen several biodv-harming developments justified now cos Metric shows an 'improvement'
2) Governance. We show there are enormous governance gaps in Net Gain that could really harm enforcement & compliance incentives - things @megcevans warns about in her work & thesis openresearch-repository.anu.edu.au/handle/1885/13…; & Quetier et al. show for France too sciencedirect.com/science/articl…
Can't encourage peeps enough to read Damiens @Ascelin @LibbyJPorter's paper here: sciencedirect.com/science/articl…. If the governance isn't solid, then compensation systems can harm us today without necessarily compensating in future, & whole logic of offsetting breaks down
3) Avoidance. It looks like Net Gain *might* be incentivising development on less ecologically valuable land - as predicted by @TopcatToni & team here: sciencedirect.com/science/articl…. Although, we need to compare avoidance before & after Net Gain to be sure, & that's very tough.
4) On-site vs off-site. Although Net Gain is often viewed as an 'offsetting policy', our data shows it's more of an 'onsetting policy' - 95% of biodv units delivered 'on-site' or right next door. Could be a real-world test of onsetting ideas of @sbekessy @M_Selinske & team.

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More from @sophusticated

9 Jun
Biodiversity Net Gain. Wish there was actual, empirical evidence about what it might really mean for your company/local authority/England’s nature?

Our @DICE_Kent-led new paper in @ConLetters reports the results of the 1st evaluation of #BNG conbio.onlinelibrary.wiley.com/doi/full/10.11…. Monster🧵
TLDR: Under #BNG, we lose open greenspace, traded for promises to deliver smaller, higher quality habitats in future. Offset system might be tiny: 95% of units in our sample delivered within development footprints themselves. Governance & the Metric need URGENT improvement.
Environment Bill is expected to mandate that all new developments under the Town & Country Planning Act achieve a mandatory net gain in biodiversity, measured using the Biodiversity Metric (3.0 released soon). Mandatory #BNG expected to be implemented nationally from autumn 2023.
Read 27 tweets
8 Mar
As an academic working on understanding & how to get the best possible nature outcomes for #Biodiversity #NetGain #BNG, let me share a major worry that I see barely discussed at all, & which unaddressed could decimate the biodiversity impacts: 'cost-shifting'. /1
Cost-shifting occurs when an offsetting / biodv compensation policy is introduced under the rationale that nature conservation is underfunded, so we need new private finance to make up the shortfall. So, we set up offsetting to charge developers for their biodv impacts. /2
Fundamental idea here is that offsetting provides funding that is *additional* ie would not have been provided before. So, it assumes that conservation funding post-introduction of offsetting = funding from government before + funding from private sector through offsetting. /3
Read 12 tweets
4 Mar
As mandatory Biodiversity Net Gain inches closer, update all on what the data says the impacts of #BNG will currently be on England's nature, without further changes. 📢📢📢Updated results of our database of all development projects within councils with Net Gain policies 📢📢 /1
Database now spans ~6000 new homes & industrial, research, transport, energy, & health/social care infrastructures; ~800 individual habitat patches. It's now a pretty good picture of where #BNG is leading. Built with @wildbusiness & team of wonderful forward-thinking planners /2
Headline results: #BNG currently associated with a 36% loss of area devoted to non-urban habitats (so urban habitats cover 16% of total footprint of development boundaries under baseline, and 50% under post-dev scenario). BUT, urban is mostly replacing croplands & pasture /3
Read 15 tweets

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